KLF15/Gap43通过抑制钙调磷酸酶活化保护糖尿病肾病足细胞的机制研究

钙调磷酸酶(CaN)活化在糖尿病肾病(DN)足细胞损伤中发挥关键作用，但其调控机制未完全阐明。钙调蛋白(CaM)是CaN活化的核心调控分子，预实验发现：生长相关蛋白43(Gap43)特异表达肾小球并与CaM结合，DN患者和高糖培养的足细胞Gap43表达降低；高糖条件下过表达Gap43，与CaM结合增加，CaN活化抑制，足细胞损伤减轻，提示Gap43可能通过结合CaM阻遏CaN活化保护足细胞。课题组前期研究显示DN患者及体外高糖培养的足细胞转录因子KLF15表达降低，进一步研究发现：体外敲低足细胞KLF15表达后，Gap43mRNA及蛋白表达明显降低，因此，课题提出：糖尿病条件下，转录因子KLF15表达降低，下调Gap43蛋白表达，导致与CaM结合减少，CaN活化，促进足细胞损伤。研究拟通过转染、IP、ChIP等技术及转基因小鼠，以证实上述科学假说。项目将为DN足细胞保护提供新理论和靶点。

Calcineurin (CaN) activation plays a key role in podocyte injury in diabetic nephropathy (DN), but the regulatory mechanism is not fully elucidated. Calmodulin (CaM) is the core regulatory molecule of CaN activation. Our preliminary experiments show that growth associated protein 43(Gap43) is specifically expressed in glomeruli and binds to CaM. The expression of Gap43 is decreased in glomerular podocyte of DN patients and cultured podocytes with high glucose (HG) in vitro. Increased Gap43 binds CaM, inhibited CaN activation and reduced podocytes damage are observed after overexpression of Gap43 in HG cultured podocytes. These results suggest that Gap43 may protect podocytes by inhibiting the activation of CaN by combining with CaM. Our previous study has demonstrated that the expression of KLF15 is decreased in podocytes of DN patients and high glucose culture in vitro. Further study showed that the expression of Gap43 mRNA and protein is significantly decreased in vitro cultured podocytes after knockdown of KLF15. Therefore, it is proposed that under the condition of diabetes, decreased transcription factor KLF15 downregulated the expression of Gap43 protein, resulting in the decrease of Gap43 binds CaM, the activation of CaN and podocyte injury. This study intends to confirm the above scientific hypothesis by transfection, IP, ChIP and other techniques as well as transgenic mice. The project is expected to provide a new theory and target for podocyte protection in DN.